Applicant's prior U.S. application Ser. No. 10/776,355 (now U.S. Pat. No. 6,883,446) which is incorporated herein by reference, describes an apparatus which permits a user to manually move a stack of fabric layers across a planar bed beneath an actuatable stitch head. The apparatus includes a detector for detecting the movement of the stack for the purpose of synchronizing the delivery of stitch strokes to the stack movement. This approach enables the insertion of uniform length stitches while allowing the user to freely move the stack within a wide range of speeds, to start or stop the stack movement at will, and to guide the stack in any direction across the planar bed.
The preferred embodiments described in said U.S. Pat. No. 6,883,446 employ a detector configured to detect stack movement within the throat space of a quilting/sewing machine by measuring the movement of at least one surface of the stack as it moves across the planar bed. As described, a preferred detector responds to energy, e.g., light, reflected from a target area on the stack surface (top and/or bottom) within the machine's throat space. The detector preferably provides output pulses representative of incremental translational movement of the stack along perpendicular X and Y directions. The output pulses are processed to determine the distance the stack moves. When the stack movement exceeds a threshold magnitude, a “stitch stroke” command is issued to cause the stitch head to insert a stitch through the stacked layers. As the user continues to move the stack across the planar bed, additional stitch stroke commands are successively issued to produce successive stitches.
Applicant's U.S. Pat. No. 6,883,446 primarily contemplates that a user directly grasp, or touch, the stacked fabric layers to push and/or pull the stack across the planar bed. However, the application also recognizes that the user could, alternatively, mount the stack on a conventional quilt frame and then grasp the frame to move the stack across the planar bed to enable the detector to sense stack surface movement.
Applicant's U.S. Application 60/571,109 filed 14 May 2004, which is incorporated herein by reference, describes alternative embodiments for controlling stitch head actuation which involve using a frame for mounting the fabric layer stack to retain it in a substantially taut condition. The frame is supported for user guided movement beneath a fixedly located stitch head and a detector is provided to produce signals representing the magnitude of frame translation, and thus the magnitude of stack translation.